Substrate processing chamber with off-center gas delivery funnel

ABSTRACT

Methods and apparatus for processing substrates are disclosed herein. The process chamber includes a chamber body, a substrate support pedestal, a pump port and a gas injection funnel. The chamber body has an inner volume and the substrate support pedestal is disposed in the inner volume of the chamber body. The pump port is coupled to the inner volume and is disposed off-center from a central axis of the substrate support pedestal. The pump port provides azimuthally non-uniform pumping proximate to a surface of the substrate support pedestal and creates localized regions of high pressure and low pressure within the inner volume during use. The gas injection funnel is disposed in a ceiling of the chamber body and opposite the substrate support pedestal. The gas injection funnel is offset from the central axis of the substrate support pedestal and is disposed in a region of low pressure.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of co-pending U.S. patent applicationSer. No. 12/240,120, filed Sep. 29, 2008, which is herein incorporatedby reference.

FIELD

Embodiments of the present invention generally relate to semiconductorprocessing chamber and, more particularly, to a method and apparatus forproviding improved uniformity in layers deposited on a substrate.

BACKGROUND

As the size of features in semiconductor devices continue to shrink,there is a continuing need to improve quality of the individualdeposited layers comprising a semiconductor device. Some qualityproblems, for instance, uniformity of a layer across a substrate can beattributed to the geometry of the process chamber in which the layer isformed or processed. For example, pump ports are often disposedasymmetrically with respect to the chamber volume, which can result inazimuthally non-uniform pumping proximate the surface of a substratebeing processed. A process gas being supplied to the substrate via a gasinlet disposed centrally above a substrate support is often distributednon-uniformly across the substrate surface, having thinner depositionproximate the pumping port.

Many techniques, for example, Physical Vapor Deposition, Chemical VaporDeposition and Atomic Layer Deposition (ALD) are well known for thefabrication of devices using thin layers. The ALD technique depositsextremely thin coatings on the substrate surface. As such, ALDtechniques are especially susceptible to non-uniform distribution ofprocess gas causing non-uniform layer deposition.

Thus, there is a need in the art for an improved process chamber forproviding improved uniformity in the distribution of a process gasacross the surface of a substrate.

SUMMARY

A method and apparatus for processing a substrate are provided herein.In some embodiments, the apparatus includes a process chamber definingan inner volume and having a substrate support pedestal disposedtherein; a pump port coupled to the inner volume and disposed off-centerfrom a central axis of the substrate support pedestal, wherein the pumpport provides azimuthally non-uniform pumping proximate a surface of thesubstrate support pedestal creating localized regions of high pressureand low pressure within the inner volume during use; and a gas injectionfunnel disposed in a ceiling of the process chamber opposite thesubstrate support pedestal, wherein the gas injection funnel is offsetfrom the central axis of the substrate support pedestal and disposed ina region of low pressure.

In some embodiments, a method of depositing a layer of material on asemiconductor substrate includes placing a substrate on a substratesupport pedestal disposed in an inner volume of a process chamber havingone or more pump ports disposed off-center from the substrate supportpedestal, wherein the one or more pump ports provide azimuthallynon-uniform pumping proximate a surface of the substrate supportpedestal creating localized regions of high pressure and low pressurewithin the inner volume; and providing a first process gas to the innervolume via a gas injection funnel disposed in a ceiling of the chamberbody opposite the substrate support pedestal, wherein the gas injectionfunnel is offset from a central axis of the substrate support pedestaland disposed in a region of low pressure and wherein the first processgas at least partially forms a layer on the substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentinvention can be understood in detail, a more particular description ofthe invention, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this invention and are therefore not to beconsidered limiting of its scope, for the invention may admit to otherequally effective embodiments.

FIG. 1 depicts a schematic cross sectional view of one embodiment of aprocess chamber in accordance with the present invention;

FIG. 2A-D depict schematic top views of embodiments of a process chamberin accordance with the present invention; and

FIG. 3 depicts a flow chart of a method in accordance with someembodiments of the present invention.

DETAILED DESCRIPTION

Methods and apparatus for processing a substrate are provided herein. Insome embodiments, the apparatus includes a process chamber defining aninner volume and having a substrate support pedestal disposed therein; apump port coupled to the inner volume and disposed off-center from acentral axis of the substrate support pedestal, wherein the pump portprovides azimuthally non-uniform pumping proximate a surface of thesubstrate support pedestal creating localized regions of high pressureand low pressure within the inner volume during use; and a gas injectionfunnel disposed in a ceiling of the chamber body opposite the substratesupport pedestal, wherein the gas injection funnel is offset from thecentral axis of the substrate support pedestal and disposed in a regionof low pressure. The apparatus and accompanying method facilitateimproved uniformity in deposited layers on the surface of a substrate.

FIG. 1 depicts a schematic cross-sectional view of an exemplary processchamber 100 in accordance with some embodiments of the presentinvention. The process chamber 100 may be adapted for a cyclicdeposition, such as Atomic Layer Deposition (ALD) or Chemical VaporDeposition (CVD). ALD and CVD used herein to facilitate sequentialintroduction of reactants to deposit a thin layer over a substratestructure. The sequential introduction of reactants may be repeated todeposit multiple thin layers to form a conformal layer of a desiredthickness. The process chamber 100 may also be adapted for otherdeposition techniques, such as Plasma Enhanced-CVD (PE-CVD), PhysicalVapor Deposition (PVD), Atomic Layer Epitaxy (ALE), or the like, orcombinations thereof. One suitable process chamber that may be modifiedin accordance with the present invention is the GEMINI™ ALD chamber,available from Applied Materials, Inc.

The process chamber 100 comprises a chamber body 102 having an innervolume 101 with a substrate support pedestal 114 disposed therein. Thechamber body 102 further comprises sidewalls 104 and a bottom 106. Aslit valve 108 in the process chamber 100 provides access for a robot(not shown) to deliver and retrieve a substrate 110. The details ofexemplary process chamber 100 are described in commonly assigned UnitedStates Patent Application Publication No. 2005-0271813, filed on May 12,2005, entitled “Apparatuses and Methods for Atomic Layer Deposition ofHafnium-Containing High-K Dielectric Materials,” and United StatesPatent Application Publication No. 20030079686, filed on Dec. 21, 2001,entitled “Gas Delivery Apparatus and Method For Atomic LayerDeposition,” both of which are incorporated by reference herein.

A substrate support pedestal 114 supports the substrate 110 on asubstrate receiving surface 112 in the process chamber 100. Thesubstrate support pedestal 114 is mounted on a lift motor 122 to raiseand lower the substrate support pedestal 114 and the substrate 110disposed thereon. A lift plate 124, coupled to a lift motor 126, ismounted in the process chamber 100 and raises and lowers pins 128movably disposed through the substrate support pedestal 114. The pins128 raise and lower the substrate 110 over the surface of the substratesupport pedestal 114. In some embodiments, the substrate supportpedestal 114 may include a vacuum chuck, an electrostatic chuck, or aclamp ring for securing the substrate 110 to the substrate supportpedestal 114 during processing. The lift motor 122, or alternativelylocated proximate the lift motor 122, is a mechanism for facilitatingrotation of the substrate support pedestal 114 about a central axisduring processing.

In some embodiments, the substrate support pedestal 114 may be heated toincrease the temperature of the substrate 110 disposed thereon. Forexample, the substrate support pedestal 114 may be heated using anembedded heating element, such as a resistive heater, or may be heatedusing radiant heat, such as heating lamps disposed above the substratesupport pedestal 114. In some embodiments, a purge ring 130 may bedisposed on the substrate support pedestal 114 to define a purge channel132. The purge channel 132 provides a purge gas to a peripheral portionof the substrate 110 to prevent deposition thereon.

A gas delivery apparatus 138 is disposed at an upper portion of thechamber body 102 to provide a gas such as a process gas, carrier gas orinert gas to the process chamber 100. A vacuum system 176 communicateswith a pumping port 178 to evacuate any unwanted gases from the processchamber 100 and to help in maintaining a desired pressure or a desiredpressure range inside the inner volume 101 of the process chamber 100.The pumping port 178 is asymmetrically disposed with respect to theinner volume 101 of the chamber body 102 and may provide azimuthallynon-uniform pumping proximate the surface 112 of the substrate supportpedestal 114.

The chamber 100, as depicted in FIG. 1, permits a gas to enter theprocess chamber 100 normal (i.e., 90 degree) with respect to the planeof the substrate 110 via a gas injection funnel 142. The gas deliveryapparatus 138 further comprises a chamber lid 140. The chamber lid 140includes the gas injection funnel 142 and a bottom surface 158 extendingfrom the gas injection funnel 142 to a peripheral portion of the chamberlid 140. The chamber lid 140 acts as a ceiling of the chamber body 102.The bottom surface 158 is sized and shaped to substantially cover thesubstrate 110 disposed on the substrate support pedestal 114. Thechamber lid 140 may have a choke 160 at a peripheral portion of thechamber lid 140 adjacent the periphery of the substrate 110.

The gas injection funnel 142 is disposed opposite the surface 112 of thesubstrate support pedestal 114 and offset from the central axis ofsubstrate support pedestal 114. The gas injection funnel 142 may includeone or more gas inlets, such as gas inlets 144, 145 for coupling the gasinjection funnel 142 to one or more gas sources, such as gas sources146, 147. It is further contemplated that other variants are possible,such as providing at least one of valves, mass flow controllers, orsimilar apparatus for controlling the flow of a gas between each gassource 146, 147 and each gas inlet 144, 145.

Referring to FIG. 1, at least a portion of the bottom surface 158 of thechamber lid 140 may be tapered from the gas injection funnel 142 to aperipheral portion of the chamber lid 140 to help in providing animproved velocity profile of the gas flow from the gas injection funnel142 across the surface of the substrate 110. The bottom surface 158 maycomprise one or more tapered surfaces, such as a straight surface, aconcave surface, a convex surface, or combinations thereof. In someembodiments, the bottom surface 158 is tapered in the shape of a funnel.

A control unit 180, such as a programmed personal computer, work stationcomputer, or the like, is coupled to the process chamber 100 to controlvarious processing conditions. For example, the control unit 180 may beconfigured to control flow of gases from gas sources 146, 147. Thecontrol unit 180 may further be configured to control the rotation ofthe substrate 110 during processing.

The control unit 180 includes a Central Processing Unit (CPU) 182,support circuits 184, and a memory 186 having associated softwareroutine 188. The Central Processing Unit 182 may be one of any form ofgeneral-purpose computer processor that can be used in an industrialsetting for controlling various chambers and sub-processors. The memory,or computer-readable medium, 186 of the CPU 182 may be one or more ofreadily available memory such as Random Access Memory (RAM), Read OnlyMemory (ROM), floppy disk, hard disk, or any other form of digitalstorage, local or remote. The support circuits 184 are coupled to theCPU 182 for supporting the processor in a conventional manner. Thesupport circuits include cache, power supplies, clock circuits,input/output circuitry and subsystems, and the like. The softwareroutine 188, when executed, can perform embodiments of the inventivemethod 300, which is described below. The software routine 188 may alsobe stored and/or executed by a second CPU (not shown) that is remotelylocated from the hardware being controlled by the CPU 182.

FIGS. 2A-D depict schematic top views of the process chamber 100 in aaccordance with embodiments of the present invention. FIGS. 2A-D furtherillustrate positioning of one or more gas injection funnels and one ormore pump ports relative to the position of the substrate supportpedestal. Generally, in the present invention, each gas injection funnelmay be disposed in the ceiling of the chamber body opposite thesubstrate support pedestal, wherein the gas injection funnel is offsetfrom a central axis of the substrate support pedestal and disposed in aregion of low pressure. Each pump port may be coupled to the innervolume and disposed off-center from the central axis of the substratesupport pedestal. Each pump port may provide azimuthally non-uniformpumping proximate a surface of the substrate support pedestal creatinglocalized regions of high pressure and low pressure within the innervolume during use.

FIG. 2A depicts a schematic top view of the process chamber 100 in aaccordance with one embodiment of the present invention. In theembodiment depicted in FIG. 2A, a central axis of each of the pump port178, the gas injection funnel 142 and the substrate support pedestal 114are disposed in a common plane. The gas injection funnel 142 and thepump port 178 are disposed opposite each other with respect to thecentral axis of the substrate support pedestal.

FIG. 2B depict a schematic top view of a process chamber 200 in aaccordance with one embodiment of the present invention. The processchamber 200 includes the substrate support pedestal 114, the pump port178, a first gas injection funnel 202 and a second gas injection funnel204. In the embodiment depicted in FIG. 2B, the central axis of each ofthe pump port 178 and the substrate support pedestal 114 are disposed ina common plane, and the first and second gas injection funnels aredisposed in regions of low pressure on opposing sides of the commonplane. The pump port and each gas injection funnel 202, 204 are disposedon opposing sides with respect to the central axis of the substratesupport pedestal 114. In some embodiments, the first and second gasinjection funnels 202, 204 may be coupled to one or more common gassources. (not shown). In some embodiments, the first and second gasinjection funnels 202, 204 may be coupled to separate gas sources forsupplying the same or different process gases.

In the configuration illustrated in FIG. 2B, the pump port 178 isdisposed about equidistant from each funnel 202, 204. It is contemplatedthat the pump port can provide substantially similar azimuthallynon-uniform pumping proximate a portion of the surface of the substratesupport pedestal 114 disposed below each gas injection inlet 202, 204.

FIG. 2C depicts a schematic top view of a process chamber 210 inaccordance with one embodiment of the present invention. The processchamber 210 includes the substrate support pedestal 114, the pump port178, a second pump port 216, a first gas injection funnel 212 and asecond gas injection funnel 214. In the embodiment depicted in FIG. 2C,a central axis of each of the pump port 178, the second pump port 216and the substrate support pedestal 114 are disposed in a first commonplane 213; and a central axis of the first and second gas injectionfunnels 212, 214 and the substrate support pedestal 114 are disposed ina second common plane 215. In FIG. 2C, and in some embodiments, thefirst and second common planes 213, 215 are perpendicular to each other.Further, as shown in FIG. 2C and in some embodiments, the pump port 178and the second pump port 216 are disposed opposite each other withrespect to the central axis of the substrate support pedestal 114; andthe first and second gas injection funnels 212 and 214 are disposedopposite each other with respect to the central axis of the substratesupport pedestal 114.

As discussed above, it is similarly contemplated here that the first andsecond gas injection funnels 212, 214 can be coupled to one or morecommon gas sources, or alternatively, each gas injection funnel 212, 214can be coupled to a separate gas source for supplying the same ordifferent process gases.

In the configuration illustrated in FIG. 2C, the pump port 178 and thesecond pump port 216 are disposed about equidistant from each funnel202, 204. It is contemplated that each pump port can providesubstantially similar azimuthally non-uniform pumping proximate aportion of the surface of the substrate support pedestal 114 disposedbelow each gas injection inlet 212, 214.

FIG. 2D depicts a schematic top view of a process chamber 220 inaccordance with one embodiment of the present invention. The processchamber 220 includes the substrate support pedestal 114, the pump port178, the second pump port 216, and the first gas injection funnel 212.In the embodiment depicted in FIG. 2D, a central axis of each of thepump port 178, the second pump port 216 and the substrate supportpedestal 114 are disposed in the first common plane 213; and a centralaxis of the first gas injection funnel 212 and the substrate supportpedestal 114 are disposed in the second common plane 215. In FIG. 2D,and in some embodiments, the first and second common planes 213, 215 areperpendicular to each other. Further, as shown in FIG. 2D and in someembodiments, the pump port 178 and the second pump port 216 are disposedopposite each other with respect to the central axis of the substratesupport pedestal 114; and the first gas injection funnel 212 is disposedin a region of low pressure substantially equidistant from each pumpport 178, 216.

FIG. 3 depicts a flow chart of a method 300 in accordance with someembodiments of the present invention. The method 300 is described belowwith respect to FIGS. 1 and 2A, however, the method 300 may be appliedusing any suitable embodiments of the process chambers described above.The method 300 begins at 302 by providing a substrate 110. Generally, acentral axis of the substrate 110 is aligned with the central axis ofthe substrate support pedestal 114.

The substrate 110 is disposed in the process chamber 100 having a pumpport 178 disposed off-center from the substrate support pedestal 114 anda gas injection funnel 142 disposed in the ceiling of the processchamber 100 opposite the substrate support pedestal 114. The gasinjection funnel 142 is offset from the central axis of the substratesupport pedestal 114 and disposed in region of low pressure.

The substrate 110 may be any substrate or material surface upon whichfilm processing is performed. For example, the substrate 110 may be amaterial such as crystalline silicon (e.g., Si<100> or Si<111>), siliconoxide, strained silicon, silicon germanium, doped or undopedpolysilicon, doped or undoped silicon wafers, patterned or non-patternedwafers, silicon on insulator (SOI), carbon doped silicon oxides, siliconnitride, doped silicon, germanium, gallium arsenide, glass, sapphire, orthe like. The substrate 110 may have various dimensions, such as 200 mmor 300 mm diameter wafers, as well as rectangular or square panels.

At 304, the pump port 178 provides azimuthally non uniform pumping isprovided to proximate the surface of the substrate 110 and substratesupport pedestal 114. The azimuthally non uniform pumping generallyprovides high pressure regions proximate the pump port 178 and lowpressure regions away from the pump port 178. In the absence ofcorrection, the inventors have discovered that azimuthally non uniformpumping results in a thinner deposition of a process gas on a portion ofthe substrate 110 proximate the pump port 178.

At 306, a process gas is provided via the gas injection funnel 142. Thegas injection funnel 142 may be purposefully offset from the centralaxis of the substrate support pedestal 114 and opposing the pump port178 with respect to the central axis of the substrate support pedestal114 as described in FIG. 2A. The gas injection funnel 142 provides theprocess gas at uneven flow rates to the substrate 110. For example, andindependent of the position of gas injection funnel 142 with respect tothe pump port 178, the gas injection funnel 142 provides a higher flowrate of the process gas to a portion of the substrate 110 disposeddirectly below the gas injection funnel 142. The higher flow rate mayresult in increase deposition (i.e., a singularity point) of the processgas on the portion of the substrate 110 located directly below the gasinjection funnel 142 as compared with any portion of the substrate 110peripheral to the gas injection funnel 142. By purposefully offsettingthe gas injection funnel 142 from the central axis of the substratesupport pedestal 114 and away from the pumping port 178, the singularitypoint may be shifted to the peripheral edge of the substrate 110 and theprocess gas may be more uniformly distributed across the surface of thesubstrate 110.

The gas injection funnel 142 is configured to provide one or moreprocess gas from the gas sources 146, 147 as depicted in FIG. 1. Forexample, in a process such as an atomic layer deposition (ALD) process,a first process gas may be provided from the gas source 146 via the gasinjection funnel 142 and deposited on the substrate 110 to at leastpartially form a layer. A second gas may be provided from the gas source147 via the gas injection funnel 142 and deposited on the substrate 110to at least partially form the layer, wherein the layer comprisingmaterials from the first and second process gases. In some embodiments,the first and second process gases are supplied simultaneously via thegas injection funnel 142 and deposited on the substrate 110 to form thelayer.

In some embodiments, the gas injection funnel 142 may provide carriergases or inert gases to the inner volume via the gas injection funnel142. The carrier gases may be provided, for example, in combination witha process gas to dilute concentration of the process gas, improvechamber pressure or the like. The carrier gas can be providedcontinuously during a deposition process, or in combination with aprocess gas as discussed. The inert gas may be provided, for example, aspart of the purging step of an ALD process, or may be providedcontinuously for purging.

At 308, and optionally, the substrate 110 may be rotated about a centralaxis by way of rotating the substrate support pedestal 114 about acentral axis. The rotation of the substrate 110 may be provided duringthe deposition of a process gas via the gas inlet funnel 142. Therotation may facilitate the uniform distribution of the process gasacross the surface of the substrate 110.

At 310, a layer may be at least partially formed on the substrate 110.In some embodiments, and as described above, by a cyclic depositionprocess, such as the ALD process. The pulsing of the first process gasfollowed by a time delay and pulsing of the second process gas comprisea deposition cycle. A cycle can start with either the first process gasor the second process gas.

In some embodiments, during the time delay, a purge gas, such asnitrogen is provided into the process chamber 100 via the gas injectionfunnel 142. In some embodiments, the purge gas may flow continuouslythroughout the deposition process so that only the purge gas is providedin the chamber during the time delay between the pulses of the firstprocess gas and the second process gas. A “pulse” as used herein isintended to refer to a quantity of a particular compound that isintermittently or non-continuously introduced into a reaction zone of aprocessing chamber.

After each deposition cycle, a layer having a particular thickness willbe deposited on the substrate surface. Depending on specific devicerequirements, subsequent deposition cycles may be needed to obtain adesired thickness. As such, a deposition cycle can be repeated until thedesired thickness is achieved.

Methods and apparatus for processing a substrate have been providedherein. The azimuthally non-uniform pumping proximate a surface of thesubstrate support pedestal may be compensated for by offsetting the gasinjection funnel from the central axis of the substrate support pedestaland in a region of low pressure. The methods and apparatus facilitateimproved uniformity in deposited layers on the surface of a substrate.

While the foregoing is directed to embodiments of the present invention,other and further embodiments of the invention may be devised withoutdeparting from the basic scope thereof.

The invention claimed is:
 1. A process chamber for processing asubstrate, comprising: a chamber body having an inner volume; asubstrate support pedestal disposed in the inner volume of the chamberbody; a pump port coupled to the inner volume and disposed off-centerfrom a central axis of the substrate support pedestal, wherein the pumpport provides azimuthally non-uniform pumping proximate a surface of thesubstrate support pedestal creating localized regions of high pressureand low pressure within the inner volume during use; and one or more gasinjection funnels disposed in a ceiling of the chamber body and directlyopposite the substrate support pedestal, wherein each gas injectionfunnel is offset from the central axis of the substrate support pedestaland disposed in a region of low pressure.
 2. The process chamber ofclaim 1, wherein the substrate support pedestal further comprises: arotatable substrate support pedestal capable of rotation about thecentral axis.
 3. The process chamber of claim 1, wherein the one or moregas injection funnels is one gas injection funnel, and wherein thecentral axis of each of the pump port, the gas injection funnel and thesubstrate support pedestal are disposed in a common plane and whereinthe pump port and the gas injection funnel are disposed opposite eachother with respect to the central axis of the substrate supportpedestal.
 4. The process chamber of claim 1, further comprising: a firstgas source and a second gas source, each coupled to the one or more gasinjection funnels.
 5. The process chamber of claim 1, wherein the one ormore gas injection funnels are a first gas injection funnel and a secondgas injection funnel.
 6. The process chamber of claim 5, wherein thesubstrate support pedestal further comprises: a rotatable substratesupport pedestal capable of rotation about the central axis.
 7. Theprocess chamber of claim 5, further comprising: a second pump portcoupled to the inner volume and disposed off-center from the centralaxis of the substrate support pedestal, wherein the combination of thepump port and the second pump port provide azimuthally non-uniformpumping proximate the surface of the substrate support pedestal creatinglocalized regions of high pressure and low pressure within the innervolume during use.
 8. The process chamber of claim 7, wherein thesubstrate support pedestal further comprises: a rotatable substratesupport pedestal capable of rotation about the central axis.
 9. Theprocess chamber of claim 7, wherein the central axis of each of the pumpport, the second pump port, and the substrate support pedestal aredisposed in a first common plane.
 10. The process chamber of claim 9,wherein the central axis of each of the first gas injection funnel, thesecond gas injection funnel, and the substrate support pedestal aredisposed in a second common plane.
 11. The process chamber of claim 10,wherein the first common plane is perpendicular to the second commonplane.
 12. The process chamber of claim 1, further comprising: a secondpump port coupled to the inner volume and disposed off-center from thecentral axis of the substrate support pedestal, wherein the combinationof the pump port and the second pump port provide azimuthallynon-uniform pumping proximate the surface of the substrate supportpedestal creating localized regions of high pressure and low pressurewithin the inner volume during use.
 13. The process chamber of claim 12,wherein the substrate support pedestal further comprises: a rotatablesubstrate support pedestal capable of rotation about the central axis.14. The process chamber of claim 12, wherein the central axis of each ofthe pump port, the second pump port, and the substrate support pedestalare disposed in a common plane.
 15. The process chamber of claim 1,wherein the pump port is the only pump port coupled to the inner volume,wherein the one or more gas injection funnels are a first gas injectionfunnel and a second gas injection funnel, and wherein a plane includinga central axis of the first and second gas injection funnels and thecentral axis of the substrate support pedestal is substantiallyperpendicular to a plane including a central axis of the pump port andthe central axis of the substrate support pedestal.
 16. A processchamber for processing a substrate, comprising: a chamber body having aninner volume; a substrate support pedestal disposed in the inner volumeof the chamber body; a pair of pump ports coupled to the inner volume,wherein the pump ports are disposed off-center from a central axis ofthe substrate support pedestal, and wherein the pump ports provideazimuthally non-uniform pumping proximate a surface of the substratesupport pedestal creating localized regions of high pressure and lowpressure within the inner volume during use; and one or more gasinjection funnels disposed in a ceiling of the chamber body and directlyopposite the substrate support pedestal, wherein each gas injectionfunnel is offset from the central axis of the substrate support pedestaland is disposed in a region of low pressure, and wherein a planeincluding a central axis of the one or more gas injection funnels andthe central axis of the substrate support pedestal is substantiallyperpendicular to a plane including a central axis of each of the pumpports and the central axis of the substrate support pedestal.
 17. Theprocess chamber of claim 16, wherein gases provided to the inner volumethrough the ceiling are only provided through the one or more gasinjection funnels.
 18. The process chamber of claim 1, wherein gasesprovided to the inner volume through the ceiling are only providedthrough the one or more gas injection funnels.
 19. A process chamber forprocessing a substrate, comprising: a chamber body having an innervolume; a substrate support pedestal disposed in the inner volume of thechamber body; a pump port coupled to the inner volume and disposedoff-center from a central axis of the substrate support pedestal,wherein the pump port provides azimuthally non-uniform pumping proximatea surface of the substrate support pedestal creating localized regionsof high pressure and low pressure within the inner volume during use;and a single gas injection funnel having an opening disposed in aceiling of the chamber body directly opposite the substrate supportpedestal, wherein the single gas injection funnel is offset from thecentral axis of the substrate support pedestal and disposed in a regionof low pressure.
 20. The process chamber of claim 19, wherein gasesprovided to the inner volume through the ceiling are only providedthrough the single gas injection funnel.